蓝光相变光盘的多层膜结构设计

为了使光盘获得优良的记录／读出性能并能够长期稳定地使用，必须优化设计相变光盘的多层膜结构。采用自行设计的模拟分析相变光盘读出过程设计软件，从光学角度出发模拟计算了蓝光(405nm)相变光盘的膜层结构，研究了多层膜系的反射率和反射率对比度等光学参量与各层膜厚度和槽深的关系。研究得出的最佳多层膜结构为：下介电层／记录层／上介电层／反射层的厚度对于台记录为100nm／10nm／25nm，／60nm，而对于槽记录则为140nm／15nm／30nm，／60nm，槽深为50nm。模拟计算结果对于将来高密度蓝光相变光盘的制备具有一定的指导意义。     

证券价格按几何布朗运动变化的微观解释

金融市场研究中经常不加解释地假设证券价格按几何布朗运动变化 .本文通过假定投资者要求来自证券的期望收益率与证券价格无关 ,在理想市场的前提条件下 ,对证券价格运动将遵循有漂移率的几何布朗运动给予严格的证明 .     

Sasakian空间形式中具有平行平均曲率向量的C-全实子流形的刚性定理

讨论了Sasakian空间形式中具有平行平均曲率向量的C-全实子流形,得到了紧致的C-全实子流形的一个刚性结果.     

Regularity of Harmonic Functions in Cheeger-Type Sobolev Spaces

We give a geometric approach to the study of the regularity of harmonic functions in Cheeger-type Sobolev spaces, and prove the Hölder continuity of such functions. In the proof, we give a definition of an upper curvature bound of the unit sphere of a Banach space, which seems to be of independent interest.     

意义世界的勘明

中国在晚近100多年的时间里,围绕着人与自然、个人与群体、道义与功利这三个基本的价值领域,经历了前现代价值系统的变革和现代价值观建构的曲折过程。今人返观此前150年价值观的变革史,可以清晰地勾勒出它渐次演进的轨迹。现代性的意义世界正在勘明。     

A note on 4-dimensional locally conformally flat Walker manifolds

A 4-dimensional Walker metric on a semi Riemanian manifold M, for the canonical metric with c = 0, have been investigated by M. Chaichi, E. García—Río and Y. Matsushita. The paper generalizes these notions to the case of constant c ≠ 0. Specially the form of defining functions of this metric in locally conformally flat 4-dimensional Walker manifolds is found.     

浅析篮球运动员的快速能力

快速能力是篮球运动员的最基础的竞技能力 ,因此 ,培养训练篮球运动员的快速能力是非常重要的 .快速能力主要包括 :移动速率 ;反应、判断力 ;果断性、合理性 ;攻守转换的速度等 .在训练中 ,应根据球队队员的特点进行 ,做到个性与共性的有机结合 ,使其得到最大限度的提高     

Nonnegative curvature and cobordism type

We show that in each dimension n = 4k, k≥ 2, there exist infinite sequences of closed simply connected Riemannian n-manifolds with nonnegative sectional curvature and mutually distinct oriented cobordism type. W. Tuschmann’s research was supported in part by a DFG Heisenberg Fellowship.     

Geometrical study of paraxial light beam transmission in free space

By introducing an imaginary space transform curvature ρ_s, a complex space called Riemannian space is constructed, in which the light propagating in free space has the trajectory of straight line while propagating. Moreover, this curvature couples with that of the wave front of the paraxial beam ρ_w, and therefore a complex curvature ρ_c is constructed, which can be employed to investigate the behavior of the light transmission and to generalize the ABCD law. Project supported by the National Hi-Tech Inertial Confinement Fusion Committee, the Guangdong Natural Science Foundation the Postdoctoral Foundation of Guangdong and National Postdoctoral Foundation of China.     

The change of the superstructure of semicrystalline polymers during deformation: results from small-angle scattering with synchrotron radiation

The change of the superstructure of different polyethylenes during uniaxial deformation is investigated. The method used is small-angle scattering with synchrotron radiation. For branched polyethylene (Lupolen 1840D) the whole deformation range is analyzed. Beginning with superstructure of the lamellar cluster type, the superstructure partly disappears on a time scale of a few minutes and the fibrillar structure is built up. The degree of destruction and rebuilding depends on the drawing temperature. For very high molecular weight polyethylene (GUR) a reversible change of the superstructure at higher deformation ratios and at different temperatures is observed. The superstructure of (ethylene—hexene) copolymers (TIPELIN) at high draw ratios depends on the drawing temperature and is almost independent of the side group content. Interfibrillar microcracks parallel to the draw direction are produced in samples with a low side group content for draw ratios λ ≥ 1.5.